<!DOCTYPE html>
<html class="reftest-wait">
<title>
Changing target to an element that does not override opacity animations
creates a stacking context even if the animation is delay phase
</title>
<style>
span {
  height: 100px;
  width: 100px;
  position: fixed;
  background: green;
  top: 50px;
}
#first {
  width: 100px; height: 100px;
  background: blue;
  opacity: 1 ! important;
}
#second {
  width: 100px; height: 100px;
  background: blue;
}
</style>
<span></span>
<div id="first"></div>
<div id="second"></div>
<script>
  var anim = document.getElementById("first")
    .animate({ opacity: [0, 1] },
             { delay: 100000, duration: 100000 });
  anim.ready.then(function() {
    anim.effect.target = document.getElementById("second");
    requestAnimationFrame(function() {
      document.documentElement.classList.remove("reftest-wait");
    });
  });
</script>
